The application of "common sense" to the problem of substance supplied a more satisfactory analytic for him than the scepticism of David Hume which reached him through a study of Kant.
In 1826 he wrote a preface to a translation of Stewart's Moral Philosophy, demonstrating the possibility of a scientific statement of the laws of consciousness; in 1828 he began a translation of the works of Reid, and in his preface estimated the influence of Scottish criticism upon philosophy, giving a biographical account of the movement from Francis Hutcheson onwards.
In 1833 he was appointed professor of Greek and Roman philosophy at the college of France and a member of the Academy of Sciences; he then published the Mélanges philosophiques (4th ed.
[1] He had already demonstrated, in his prefaces, the possibility of a psychology apart from physiology, of a science of the phenomena of consciousness distinct from the perceptions of sense.
They were, according to his analysis, personal will, primitive instincts, voluntary movement, natural and artificial signs, sensibility and the faculties of intellect; on this analytic he founded his scheme of the universe.
Every man being organized in a particular way has, of necessity, an aim, the fulfilment of which is good; and he has faculties for accomplishing it, directed by reason.
But he does not follow his idea into the details of human duty, though he passes in review fatalism, mysticism, pantheism, scepticism, egotism, sentimentalism and rationalism.
His enthusiasm, and his command over the language of popular exposition, made him a great international medium for the transfusion of ideas.